But Claire Phillips, director of policy at the Office of the Children's Commissioner, said she was concerned the scheme could draw attention from the fact that children are more at risk from people they know than complete strangers.

"Introducing a version of Megan's Law in the UK would do nothing to help parents keep their children safe from sex offenders," she said.

"In fact, it could increase the risk of sexual abuse from strangers as offenders could be forced underground after being released into the community, making it more difficult for authorities to monitor them.

"And it could encourage vigilante activity within communities."

Ms Phillips said she would prefer to see more emphasis on early therapy for the victims of sexual abuse.

'No pressure'

Home Office Minister Gerry Sutcliffe is set to travel to the US to learn about the operation of Megan's Law.

Under the system, a number of states list offenders' details on the internet, allowing parents to enter their zip code (post code) or a name, to check if anyone on the register has moved in nearby.

It was introduced following the murder of seven-year-old Megan Kanka in July 1994 by known paedophile Jesse Timmendequas.

Downing Street denied that by considering the measure it was caving into pressure from the tabloids.

The prime minister's spokesman said it was not "rushing into" anything but had to balance public concern about the issue and access to information that will reassure them.

Both the Conservatives and Liberal Democrats have warned Mr Reid against backing a campaign "to gain a few headlines".